Telephone system



Dec. 22, 1931. J. 1. BELLAMY TELEPHONE SYSTEM Filed Nov. 30, 1928 PANEL SWITCH m T CA w WM M 0 C STEPPING POLARIZED FUNDAMENTAL CIRCUIT PANEL SWITCH l l l 1 i I l l I l l l FUNDAMENTAL J CIRCUIT SENDER CONT; CONT Imran-nr- Jul-1n LBeHam Wt- Patented Dec. 22, 1931 UNITED STATES PATENT OFFICE J'OHN I. BELLAMY, OF BROOKFIELD, ILLINOIS, ASSIGNOR TO RESERVE HOLDING GOM- rm, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE rnmrnonn svsrmr Application filed November 30, 1928. Serial No. 322,630.

The present invention relates to telephone systems in general, but is concerned more particularly with telephone systems wherein automatic switches are employed in setting up connections, and the main object of the present invention is to provide anew and improved control circuit for use in a reverting control circuit extending between an automatic switch and a sender from which the switch is controlled.

In general, automatic switches in telephone systems are controlled in two distinct ways. The so-called step-by-step switches are controlled by trains of impulses transmitted thereto from a subscribers line or from a register sender, and they are arranged to respond to these impulses to set up the desired connection. These switches are operated by stepping magnetsfor the most part and are more or less distinct from the typeof system wherein the switches are driven from a common mechanical power system and their movement is brought about by an engagement of an electromagnetically operated clutch.

In systems of the latter type the revertive system of control is largely used owing to the fact that it seems to be more reliable and easier to apply in a power-driven system.

In a system of this sort the switches are controlled from senders, which in turn are set either by impulses received fromsubscribers lines or from an operators switchboard,and the control circuit extending between a switch .and the sender has come to be known as the fundamental circuit. There are a large number of patents dealing with the numerous aspects of power-driven systems. One such patent is No. 1,395,977, grantedto F. A.

.Stearn and'F. J. Scudder, November 1, 1921'.

This patent deals with a'system employing power-driven switches of the so-called panel type, a type developed by the Western Electric Company and installed in several cities of the United States.

The control of the fundamental circuit. will now be briefly outlined. After the registering portion of the sender has been set, or partly so, the fundamental circuit is closed in the sender, operating a line relay in the first panel switch to be operated, responsive to stepping relay of the sender falls back. The

result is that the stepping relay operates when the fundamental circuit is first closed and falls back each time the panel switch moves a predetermined distance. The operations of the stepping relay in the sender are counted by a series of counting relays and, depending upon the setting of the associated registering apparatus, the fundamentalcircuit is opened in the sender after the required extent: of movement istaken by the panel switch. When the time arrives for the next movement of the panel switch,the fundamental circuit is again closed in the sender, whereupon the action is repeated, it being understood, of course, that circuit shifting devices known as sequence switches operate between the'two movements so that the second movement of the panel switch is not merely a continuation of the first.

"Since the stepping relay in the sender is short circuited in the panel switch instead of having its circuit opened, it has a tendency to be sluggish in responding to the movement of the panel switch. This has been taken care of in the past by a very careful balancing of the fundamental circuit, adding resistance to short loops and cutting it out again'upon the extension of the call to 'adistant oflice and the like. Of course, this is that when the holding circuit for the line relay in the panel switch is closed upon the movement of the panel switch and by the switch commutator, the current flow is reversed in the fundamental circuit instead of being discontinued, a polarized stepping relay being used in the sender.

Referring now to the drawings comprising Figs. 1 and 2', they show by means of the usual circuit diagrams a sufficient amount of apparatus in a system embodying the features of the invention to enable the same to be understood. Fig. 1 shows a portion of a panel switch, a portion of a sender, and a fundamental circuit extending between the two. Fig. 2 shows a similar sender and a panel switch having a modified line relay and a modified commutator arrangement.

Referring now particularly to Fig. 1, this drawing shows a fundamental circuit extending from a polarized stepping relay in a sender to ground and to the usual line relay in a panel switch. Above and to the right of the line relay, there is shown the commutator of the panel switch and the commutator brush. This commutator is a metallic strip having insulated openings therein as shown. The lower terminal of the line relay is connected to the negative pole of the usual exchange battery, the ungrounded pole, while the commutator strip, which has heretofore been connected to ground, is in this case connected to a battery having the negative pole thereof grounded and the positive pole ungrounded.

WVhen the registering portion of the sender has been set, the circuit is closed as shown through the full lines and dotted lines, whereupon the line relay operates and the panel switch starts to move. The polarized relay in the sender also operates in series with the line relay and closes its control contacts. As the panel switch moves, the brush passes over the conducting segments of the com mutator. Each time it does so, a local circuit is closed for the line relay including the regular exchange battery and the commutator-strip battery in series. When this circuit is closed, the current flow over the fundamental circuit and through the polarized steppingrelay is reversed, with the result that the stepping relay retracts its armature. Each time the commutator brush passes onto aninsulated segment, the local circuit for the line relay is opened and the current flow in the fundamental circuit is reversed back to normal, whereupon the polarized stepping relay again operates and closes the control contacts. This operation continues until the counting relays or other counting apparatus that the sender may contain arrives 1n a condition predetermined by the registering apparatus, whereupon the fundamental circuit is opened in the sender causing the line relay in the panel switch to fall back and stop the movement of the switch.

Referring now to Fig. 2, the disclosure therein is the same as Fig. 1 as regards the sender and is similar as regards the panel switch, the difference being that a double wound line relay is provided and the commutator has two segments and two brushes instead of one segment and one brush as in Fig. 1. This makes possible the use of the regular exchange battery for the commutator and therefore no special battery is needed as in the case of Fig. 1.

WVhen the fundamental circuit of Fig. 2 is closed through the line relay and the polarized stepping relay through the full lines and dotted lines, shown in the drawings, both relays pull up and the panel switch starts to move as a result of the operation of the line relay. As the panel switch operates the brushes move over the commutator segments. Each time the brushes encounter conducting portions of the commutator strips, a local holding circuit is closed for the line relay and the current flow is reversed in the fundamental circuit causing a retraction of the armature of the polarized stepping relay to open the control contacts. Each time the brushes pass from a conducting to an insulated segment, the local holding circuit of the line relay is opened and the normal current flow is resumed over the fundamental circuit with the result that the stepping relay reoperates. When the panel switch has advanced the distance predetermined by the register setting in the sender and the fundamental circuit is opened therein, the polarized stepping relay and the line relay both fall back and the movement of the panel switch ceases as a result of the deenergization of the line relay.

The arrangement of Fig. 2 has the advantage that no separate battery is required, the regular exchange battery being used for the right-hand commutator strip, the left-hand one being grounded.

What is claimed is:

1. In combination, an automatic switch and a sender arranged to exercise a mutual control over each other through an interconnecting circuit, a current source, circuit connections in said automatic switch for supplying current to said interconnecting circuit from said source, and means in said automatic switch for intermittently reversing the current flow in said interconnecting circuit from said source during the operation of said switch while maintaining said connections intact.

2. In combination, an automatic switch, a switch-controlling sender, a fundamental control circuit extending from the sender to the switch, a polarized stepping device in said sender included in said fundamental circuit, means for closing said fundamental circuit, a line relay in said automatic switch arranged to cause the switch to advance while the circuit is closed, a current source associated with said line relay having a given pole grounded and the other said fundamental circuit t rough the windingof said line relay to supply current to the fundamental circuit, another current source associated with said automatic switch and having the opposite pole thereof grounded, and means in the automatic switch for intermittently connecting the ungrounded pole of said other current source directly to the fundamental circuit a number of times depending upon the extent of the movement of the automatic switch, the polarized stepping device in said sender being responsive to the reversal of current-flow which takes place each time the said other current source is connected to the fundamental circuit.

3. In combination, an electro-responsive device, a sending device for controlling the operation of said responsive device, a control circuit extending between said sending device and said responsive device over which said control is arranged to be effected, means operative during the operation of said responsive device to transmit controlling impulses to said sending device, each impulse being opposite in polarity to the preceding impulse, and a single current source for supplying the current comprising all of said impulses.

4. In a telephone system, a selector switch, a sending device for controlling the operation of said switch, said sending device including a counting device, a fundamental circuit extending between said sending device and said selector switch, circuit connections in said selector switch for supplying current to said fundamental circuit in a given direction, means operative during the selective movement of said selector switch to intermittently supply current to said fundamental circuit in the opposite direction while maintaining said circuit connections intact, a polarized relay in said sending device having contacts operative responsive to the intermittent reversals of current-flow in said fundamental circuit, and an operating circuit for said counting device controlled by the contacts of said polarized relay.

In witness whereof, I hereunto subscribe my name this 28th day of November, A. D.

JOHN I. BELLAMY.

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